Agriculture and PesticidesUnit 7

What do humans need to survive?

• Three major biological molecules:– Carbohydrates (sugar, starch)– Lipids (fats, oils)– Proteins

• All three molecules are necessary for cellular respiration and making up the human body

• Also need vitamins and minerals (inorganic elements)

What if we don’t get what we need?

• U.N. Food and Agricultural Organization (FAO) estimated that 828 million people lack access to the food needed to be healthy and productive most in developing nations

What if we don’t get what we need?

• Average adult needs 2,600 kcal per day• Undernourished = consume less

calories than needed• Malnourished = consume enough

calories, but not enough of a specific vitamin, mineral, molecule, etc.

• Both conditions can lead to poor physical and mental development

What if we don’t get what we need?

• Marasmus = emaciation caused by a diet low in both calories and protein, very common in young children, slow growth, atrophy, can be reversed with proper diet

• Kwashiorkor = protein deficiency, edema, dry/brittle hair, stunted growth, mental retardation, swollen abdomen, can be treated with proper diet

Too much of a good thing…

• Overnourished = too many calories and nutrients, can result in obesity, diabetes, heart failure, etc.

Food distribution• Human population continues to grow

producing enough food continues to be a problem

• Food production can be increased for the short term, but can it be maintained for the long term?

• Famine = widespread shortage of food, can be caused by fire, flood, war, etc.

Maintaining Grain Stockpiles

• World grain carryover stocks = amounts of rice, wheat, corn, and other grains remaining from previous harvests

• World food security = goal in which all people have access at all times to adequate amounts of food

• World stockpiles are currently falling

Poverty and Food• Currently, enough food is produced

so that everyone could have an adequate (not generous) diet

• People are still starving to death food is not evenly distributed

• Poverty means that many people cannot afford food

Economic and Cultural Effects on Human

Nutrition• It costs a lot of money to produce, store,

transport, and distribute food• Areas with the greatest need often have

the least resources• Dishonest or ineffective governments

can also prohibit food from reaching the people who need it

Economic and Cultural Effects on Human

Nutrition• Cultural acceptance can play a large

role in whether people eat certain foods• Different foods may not be accepted

some people eat insects, dog meat, etc.• Food may not be eaten due to religious

reasons• Overall, there has been a trend toward

greater uniformity in the food we eat

Plants and Animals that Stand Between People

and Starvation• 100 species

provide 90% of the food that humans consume either directly or indirectly

• 15 plant species provide bulk of food for humans

• Sugarcane• Corn (maize)• Rice, paddy• Wheat• White potato• Cassava (manioc)• Soybean• Barley• Sweet potato• Sorghum • Peanuts (ground nuts)• Oats• Rye• Beans, dry• Peas, dry

Types of Agriculture• Industrialized agriculture (high-input

agriculture) = common in developed countries, large inputs of capital and energy to run machinery, irrigate crops, make fertilizers, etc. result in high yields (amount of a food crop produced per unit of land)

• This reduces the amount of farm land needed, but can degrade the soil, increase pest resistance, etc.

Types of Agriculture• Subsistence agriculture =

production of enough food to feed oneself and one’s family, with little left over to sell or reserve for hard times

• Requires large input of energy, but it comes from humans and farm animals

Types of Agriculture• Shifting cultivation = form of

subsistence agriculture; short periods of cultivation are followed by longer periods of the land lying fallow (uncultivated) in which the land reverts to forest

• Supports relatively small populations; requires a lot of land per person

Types of Agriculture• Slash-and-burn = form of subsistence

agriculture; involves clearing small patches of rainforest to plant crops

• Tropical rainforest soils do not have many nutrients, so farmers must move their plot every 3 years or so

Types of Agriculture• Nomadic herding = form of

subsistence agriculture; livestock is supported by land that is too arid for successful crop growth

• Herders must constantly move their livestock to find adequate food

Types of Agriculture• Intercropping = intensive form of subsistence

agriculture; involves growing a variety of plants simultaneously on the same field

• Monocultures = certain crops that produce higher yields when grown together

• Different pests are found on each crop, preventing the build-up of any one pest

• Native Americans practiced intercropping corn, beans, and squash roots all at different depths, beans perform nitrogen fixation

• Polyculture = complex form of intercropping; plants that mature at different times are planted together and harvested throughout the year

Effect of Domestication on Genetic Diversity

• Recall: Greater genetic diversity contributes to a species’ long term survival by providing the variation that enables each population to adapt to changing environmental conditions

• Domesticated = adapted to humans; a plant or animal that has been so altered from their original ancestors that it is doubtful they could survive and compete successfully in the wild; greatly reduced genetic diversity

Effect of Domestication on Genetic Diversity

• Today, we have very little genetic diversity in our livestock and crops

• These species do not need to survive in the wild they are watered, fed, fertilized, protected from pests and predators, immunized against disease, etc.

• However, when a disease does break out in a domesticated population, it evolves rapidly and spreads rapidly, causing greater losses than those that would occur in a natural, varied population

Global Decline in Domesticated Plant and

Animal Varieties• There is a global trend to replace local

varieties and breeds with just a few kinds• Local breeds are becoming scarce or even

extinct• To preserve older, more diverse varieties of

plants, many countries are collecting germplasm any plant or animal material that may be used in breeding, including seeds, plants, plant tissues, sperm, eggs, etc.

Who owns crop diversity?• Companies develop species from germplasm, and then

sell them to farmers• Plant breeders want free access to germplasm,

agricultural firms want to patent it and sell it• International Treaty on Plant Genetic Resources

for Food and Agriculture = FAO adopted it in 2001, limits the genetic materials that agricultural companies are able to patent and allows farmers to save, use, exchange, and sell farm-saved seeds. Germplasm is available to plant breeders for a royalty fee. The United States has not signed or ratified the treaty.

Increasing Crop Yields• Farmers have been using selective

breeding to increase crop yields for tens of thousands of years

• Irrigation and fertilization are also ancient practices

• Recent practices include pesticides and genetic engineering

The Green Revolution• The production of more food per

acre of cropland by using modern cultivation methods and new, high-yielding varieties of certain staple crops

• Inorganic fertilizers, mechanized machinery, pesticides, etc.

Problems with the Green Revolution

• Developing countries are dependent on imported technologies at the expense of traditional agriculture

• High energy costs fossil fuels• Disruption to water cycle via irrigation,

building canals, dams, etc.• Benefits large landowners, but not subsistence

farmers• Disrupts local ecology on a larger scale

Increasing Crop Yields in the Post-Green Revolution

Era• World demand for rice, wheat, and corn will

increase by 40% by 2020 due to increase in population and number of people who can afford meat

• Best arable land is already cultivated increasing amount of farmland won’t work

• Freshwater shortage, increased cost of agricultural chemicals, deteriorating soil quality, etc.

• What can we do?

Increasing Crop Yields in the Post-Green Revolution

Era• Scientific efforts to improve crops

genetic engineering• More efficient irrigation• Soil conservation

Increasing Livestock Yields

• Hormones = chemical messengers produced by a living organism; helps regulate growth, reproduction, and other important biological functions

• Hormones are usually given to livestock via ear implants

Increasing Livestock Yields

• European Union currently bans all imports of hormone-treated beef because of health concerns for human consumers

• Could cause cancer or affect growth of young children

• Hormones are in meat, but also present in cattle waste, which makes its way to our drinking water

Increasing Livestock Yields

• Antibiotics = chemicals used to kill bacteria and prevent disease

• Antibiotics are found in low doses in most livestock

• An animal that has been given antibiotics tends to have 4-5% more weight than other animals, probably because they aren’t using as much energy to fight infections

• Problem: Using antibiotics in livestock makes them less effective in humans bacteria are evolving to resist them

Food Safety• In the United States, there are about 76 million

cases each year of food-borne illnesses• 325,000 require hospitalization; 5,000 result in

death• USDA addresses safety of meat, poultry, and

products that contain meat or poultry• U.S. Food and Drug Administration (USFDA) is

responsible for all other foods, such as fresh produce, milk, seafood, canned foods, and processed foods that do not contain meat

Food Safety• Health experts say that the

greatest risks come from bacteria, viruses, parasites, etc.

• Food additives, pesticide residue, allergenic substances, etc. are of concern, but not nearly as important

• Do you agree?

Food Safety• There has been a 23% decline in

food borne illnesses since 1996• This is probably due to increased

surveillance and improved technology

• It is now easier to trace and stop an outbreak

Food Processing and Food Additives

• Two major aspects of food processing:

• Drying, freezing, canning, pasteurizing, curing, irradiating, etc.

• Food additives = chemicals that enhance the taste, color, texture, nutrition, etc. of food

Food Processing and Food Additives

• Sugar and salt = two most common food additives

• Can be used to make food taste better or to preserve it (fruit jelly, salted meat)

Food Processing and Food Additives

• Coloring agents = used to make food visually appealing natural or synthetic

• Preservatives = chemicals added to food to retard the growth of bacteria or fungi that would cause the food to spoil sodium propionate, potassium sorbate, etc.

• Antioxidants = chemicals that prevent oxidation butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT)

Food Processing and Food Additives

• Nitrates (compounds with NO3-) and

nitrites (compounds with NO2-) are

used as food additives for curing meats• Can react with other chemicals in food

or tobacco to form N-nitroso compounds in the stomach can cause cancer

Protection of the Consumer

• USFDA is charged with the responsibility of monitoring food additives

• 1958 – Any new food additive must undergo extensive toxicity testing before it is declared “safe”

• Additives used prior to 1958 do not have to undergo such testing

• Some have been tested and deemed safe, some have been banned not all have been thoroughly tested

Are Food Additives Bad?• Cancer, health problems, etc. vs.

cheap, easy to access and preserve food

• Concern that chemicals will act synergistically, or that the total effect will be greater than the sum of their individual effects

• Natural vs. synthetic additives

The Environmental Impacts of Agriculture

• Agriculture can impact the ability of nonagricultural terrestrial and aquatic ecosystems to provide ecosystem services clean air, clean water, fertile soil, etc.

• Produces pollution air pollution, water pollution, nitrates from animal waste, etc.

The Environmental Impacts of Agriculture

• Shift in methods small family farms to large corporate farms

• Livestock is crammed into small pens in large buildings high concentration results in lots of waste and high risk of disease

• Pesticides result in insects and weeds that are resistant, also kill aquatic life

The Environmental Impacts of Agriculture

• Degradation = natural or human-induced process that decreases the future ability of the land to produce crops or support livestock

The Environmental Impacts of Agriculture

• How much water do we need to grow crops?

• 1,000 tons of water = 1 ton of grain• 70% of freshwater use

The Environmental Impacts of Agriculture

• Habitat fragmentation = dividing a habitat into small, fragmented pieces

• Clearing grasslands and forests, draining wetlands

• 90% of North American tallgrass prairie = converted to agriculture

Using more land for cultivation

• We use about the same amount of land for agriculture as we did 50 years ago

• Almost all of the most fertile land is already being farmed, though some is lost to urbanization

• The amount of dry land being irrigated has increased 70% of the world’s total irrigated land is in Asia, and the number continues to grow

Moving towards sustainable agriculture

• Sustainable agriculture, aka alternative or low-input agriculture, relies on beneficial biological processes and environmentally friendly chemicals that disintegrate quickly and do not persist as residues in the environment.

Moving towards sustainable agriculture

• Combining modern agricultural techniques with traditional farming methods

• Planting a variety of crops to protect the farmer against unexpected changes in the marketplace and disease

• Breeding disease-resistant crops and maintaining animal health instead of relying on antibiotics

Moving towards sustainable agriculture

• Conserving water and energy• Using natural predator-prey

relationships instead of chemical pesticides birds, other bugs, etc.

• Growing crops in ideal areas In Oregon, apples don’t have major pest problems but peaches do. In Colorado, the opposite is true.

Moving towards sustainable agriculture

• Soil preservation through crop rotation, conservation tillage, contour plowing, etc.

• Adding animal manure to soil to reduce need for synthetic fertilizer

• Using soybeans for nitrogen fixation between crops

Moving towards sustainable agriculture

• Organic agriculture = no pesticide chmicals

• Integrated pest management (IPM) = limited use of pesticides, but incorporated with crop rotation, disease-resistant crops, biological pest controls, etc.

Making Subsistence Agriculture Sustainable

and More Productive• Traditional slash-and-burn is sustainable only

for a few farmers and large areas of rainforest 20-100 years of lying fallow

• Too many farmers using the slash-and-burn method = loss of tropical rainforest and soil fertility

• Heavy mulching with organic material can help the soil maintain its fertility and prevent erosion

• Planting several crops together reduces insect damage

Genetic Engineering• Taking a gene from a cell of one kind of

organism and placing it into a cell of an unrelated organism where it is expressed transgenic organism

• Selective breeding has been used for centuries

• Genetic engineering changes everything ANY organism can be used

Genetic Engineering• In theory, we could grow a plant that contains

all essential amino acids• In 2000, we successfully engineered rice

grains to produce beta-carotene, which the body uses to produce vitamin A prevents blindness and protein deficiency

• 250 million children have vitamin A deficiency• http://www.youtube.com/watch?v=TPRqRjCT_vE • http://www.youtube.com/watch?feature=endscreen&v=P406H

NSu5X8&NR=1

Genetic Engineering• Crops can be engineered to be resistant

to pests, viral diseases, drought, cold, heat, herbicides, salty or acidic soils, etc.

• This means more land could become farmland more food can be grown

• Livestock can be engineered to produce more offspring, be larger, immune or resistant to diseases, pests, etc.

Genetic Engineering• Genetically modified crops are

grown on 75 million acres of US soil

• USA is the world’s top producer of GMOs (genetically modified organisms)

• Most of these crops are regulated by the USFDA

Safety of Genetic Engineering

• Could GMOs cause ecological or health problems?

• For the most part, scientists feel that genetic engineering is safe, and many regulations have been relaxed

Biosafety Protocol• Supplement to the 1992 U.N.

Convention on Biological Diversity• Needed 50 nations to ratify it May

2003• Ensures safe transfer, handling, and use

of GMOs lessens the threat of gene transfer to wild species

Backlash Against Genetically Modified Food• Movement began in late 1990s and

early 2000s• Some fears are unfounded, some are

based on economics, and some are based on legitimate scientific concerns

Backlash Against Genetically Modified Food• Modified genes could spread to

wild species of plant or even weeds

• Transgenic organisms could cause allergic reactions in people, especially peanut varieties

Should Genetically Modified Crops be

Labeled?• People have the right to know what they

are buying and eating• The government and food companies

don’t want to cause public panic• GMOs would have to be kept separate

from non-GMOs during planting, harvesting, shipping, etc. a lot of extra cost

Another source of food…• The ocean 90% of marine catch are

fish, 6% are squid, octopus and mollusks, 3% are crustaceans, 1% are various kinds of algae

• Seafood is highly nutritious high quality protein, easily digestible

• Annual fish harvest is increasing dramatically

Problems for the Fishing Industry

• No one nation has a claim on the open ocean

• Severe overharvesting• More sophisticated fishing

equipment = most or all of the fish in an area can be harvested

• Satellites and sonar

Types of Fishing

Types of Fishing• Pots and traps = crabs, lobsters,

etc.

Types of Fishing• Longline fishing = uses bait and

hooks to catch fish, can be adjusted for different depths

Types of Fishing• Bottom gillnets = nets stretched

across the ocean floor, held in place by weights and floats

Types of Fishing• Dredges = towed along behind a

boat along the floor of an ocean, usually for harvesting oysters, scallops, etc.

Types of Fishing• Bottom trawls =

towing a net at the bottom of the ocean or just above the benthic zone; usually used to catch tuna, squid, shrimp, etc.

Types of Fishing• Purse seine net = top of net has

floats, bottom of net has weights and is pinched shut, used to catch fish that swim near water’s surface

Effects of Fishing on Environment

• Dragging nets along bottom of ocean destroys habitats

• Bycatch = organisms caught by mistake, such as dolphins, turtles, etc.

• Bycatch can be tossed back into the ocean, but most of them will die from being crushed by fishing equipment or being out of the water for so long

Fishing Laws• Magnuson Fishery Conservation Act =

1977; established eight regional fishery management councils that developed fishing plans for their own region, managers were pressured to set quotas that were too high

• Magnuson-Stevens Fishery Conservation and Management Act = 1996; required regional councils to protect “essential fish habitats” and set more strict quotas

Pollution and Fishing• People are dumping waste into the

ocean destroys habitat and kills fish

• Heavy metals (lead, mercury, etc.) can accumulate in fish and eventually be ingested by humans

Aquaculture• The rearing and harvesting of

aquatic organisms, closer to agriculture than fishing

• Cultivation of marine organisms is sometimes called mariculture

• Farmers control diets, breeding cycles, environmental conditions, etc.

Aquaculture• Can provide much needed protein• 6% of all seafood consumed• $900 million a year industry in the United

States• Labor intensive• Fishing limit is the size of natural population,

Aquaculture limit is the amount of space being used

• Compete for space on coastlines with harbors, recreational beaches, natural habitats, etc.

Pesticides• Pest = any organism that interferes in some

way with human welfare or activities (compete for food, cause disease, etc.)

• Pesticide = toxic chemical that can be used to kill pests

• Classified by what they eliminate insecticides kill insects, herbicides kill plants, fungicides kill fungi, rodenticides kill rodents, etc.

The “Perfect” Pesticide• Narrow-spectrum pesticide =

kills only the organism for which it is intended and does not harm other species

• Easily broken down, does not accumulate in organisms or environment

Reality• Broad-spectrum pesticides =

kill a variety of organisms, including some that are beneficial

• Do not degrade easily• Accumulate in organisms and

environment

First generation pesticides

• Before the 1940’s, pesticides were either naturally occuring inorganic compounds (minerals) or organic compounds

• Heavy metals such as lead, mercury, and arsenic = very toxic to pests, but also to humans no longer used

• Botanicals = plant-derived pesticides, such as tobacco or chrysanthemum

Second generation pesticides

• Synthetic botanicals = human-made insecticides produced by chemically modifying the structure of natural botanicals

• After 1940’s, more synthetic pesticides began to be used

• Dichlorodiphenyltrichloroethane (DDT) = insect killing synthetic pesticide; discovered in 1939 textbook example of biomagnification

• Silent Spring by Rachel Carson 1963, brought environmental problems caused by pesticides to public attention

Major Groups of Insecticides

• Chlorinated Hydrocarbon = organic compound containing chlorine (ex. DDT)

• Broad-spectrum pesticides• Slow to degrade• Widely used from 1940’s-1960’s, but

most have now been banned• Still in use in United States: endosulfan,

lindane, and methoxychlor

Major Groups of Insecticides

• Organophosphates = organic compounds that contain phosphorus, developed during WWII as an outgrowth of German research on nerve gas

• Highly toxic to insects, birds, aquatic life, etc.• Do not persist as long in the environment as

chlorinated hydrocarbons more commonly used

• Examples: methamidophos, dimethoate, and malathion

Major Groups of Insecticides

• Carbamates = derived from carbamic acid

• Broad-spectrum• Not as toxic to mammals• Examples: carbaryl and aldicarb

Major Kinds of Herbicides• Selective herbicides = only kill

certain types of plants• Nonselective herbicides = kill all

vegetation• Broad-leaf herbicides = kill broad-

leaf plants, not grasses• Grass herbicides = kill grasses, not

broad-leaf plants

Herbicides and the Vietnam War

• From 1962 to 1971, the United States sprayed more than 12 million gallons of herbicides over 4.5 million acres of South Vietnam to kill vegetation for improved visibility

• Agent White, Agent Blue, and Agent Orange

• Negative impacts still being felt today

Herbicides and the Vietnam War

• 14% of mangrove forests and 30% of hardwood forests were destroyed

• Health problems Agent Orange contained minute amounts of dioxins, which were 1000 times more toxic than those in domestic herbicides

• High doses can cause birth defects, reproductive disorders, and soft tissue cancers

• http://www.youtube.com/watch?v=GJxb7CY13uc = Agent Orange

• http://www.youtube.com/watch?v=bCqok_UvwY0 = Short Agent Orange

Benefits of Pesticides• Control disease fleas and lice carry typhus,

mosquitoes carry malaria, West Nile virus, dengue fever, etc.

• Not many drugs available to fight malaria focus on killing the mosquitoes that carry it

• DDT is really effective against mosquitoes In Sri Lanka in the 1950’s, DDT was used and malaria cases dropped to almost zero DDT discontinued = back almost immediately

Benefits of Pesticides• Protect our crops reduce amount lost

to pests and pathogens (microorganisms that cause disease)

• Economic benefit: Farmers save $3-5 for every $1 spent on pesticides

• Crops saved by pesticides can be the difference between life and death in developing nations

Evolution of Genetic Resistance

• Genetic resistance = any inherited characteristic that decreases the effect of a pesticide on a pest

• Many pests now have multiple resistances to several pesticides and at least 17 species have resistances to all major classes of pesticides

Evolution of Genetic Resistance

• Every time a pesticide is used, some organisms survive

• Their offspring inherit the resistance evolution

• Short generations, large populations speed up process

• Pesticide treadmill = the cost of applying pesticides increases while their effectiveness decreases

Resistance Management• Relatively new approach• Try to delay evolution of genetic

resistance• Keep a “refuge” of untreated plants

nearby allows weaker genes to survive and stay in population

• Removing resistant plants before they can flower

• Mechanically pulling weeds

Imbalances in the Ecosystem

• Pesticides affect species other than the pests for which they are intended

• Beneficial species can be killed off too• Pesticides can harm species even if they

do not kill them more vulnerable to predators or disease, unable to reproduce, etc.

Creation of New Pests• Using pesticides can remove

natural predators, parasites, competitors, etc. of a minor parasite

• The new conditions allow the minor parasite to thrive now a major parasite

Persistance, Bioaccumulation, and

Biological Magnification• Persistance = characteristic of extremely

stable chemicals; take many years to be broken down into simpler forms by natural processes

• Bioaccumulation = also called bioconcentration; buildup of a pesticide in an organism’s body

• Biological magnification = also called biological amplification; pesticide concentrations increase with trophic levels

Mobility in the Environment

• Pesticides tend not to stay where they are applied, but move through the soil, water, and air widespread effects

• Environmental Working Group (EWG) analyzed herbicides in drinking water 14.1 million Americans drink water that contains traces of five widely used herbicides

Risks of Pesticides to Human Health

• Pesticides poison ~67,000 people in the United States each year

• ~3 million people in the world are poisoned each year, 220,000 will die

• Most are people who handle pesticides on a regular basis farmers, exterminators, etc.

• Symptoms of exposure may include: nausea, vomiting, headaches, permanent damage to nervous system or other organs, cancer, sterility, birth defects, or death

Bhopal Disaster• December 1984, India – 36 metric tons

of methyl isocyanate (MIC) erupted from an underground storage tank at a Union Carbide pesticide plant after water leaked in and caused an explosive reaction

Bhopal Disaster• Toxic cloud settled over 30 square miles,

exposing up to 600,000 people• 2,500 people were killed outright, 2,500 have

died since then• Other survivors had serious respiratory,

ophthalmic, intestinal, reproductive, and neurological problems

• Young women who were exposed were unable to be married because it was assumed they were sterile

Bhopal Disaster• In 1989, Union Carbide agreed to pay

$470 million in compensation and $100 million to build a hospital for the victims

• Indian government “still dispersing” the $470 million

• Most victims have received around $500 each

Bhopal Disaster• Cleanup of contaminated land and

groundwater still needs to be addressed• Still contaminated by heavy metals and

persistent organochlorine compounds • People living in the area are still at risk• http://www.youtube.com/watch?v=GfMT

APfoC6w

Long-term Effects• Long-term exposure to pesticides =

greater risk for cancer• Lymphoma, leukemia, brain cancer,

testicular cancer, lung cancer, breast cancer

• Sterility, miscarriages, birth defects, immunity disorders, Parkinson’s disease

• Endocrine disruptors = interferes with human and animal hormones

Pesticides and Children• Children are more exposed to household

pesticides than adults play on floors and lawns, accidental ingestion

• More sensitive because they are still growing and developing

• Cancer, delayed motor skill development, mental handicaps, etc.

Alternatives to Pesticides• Interplanting crops alternating

rows of plants• Pests have trouble breeding, more

competition, etc.

Alternatives to Pesticides• Strip cutting – one segment of a

crop is harvested at a time• Unharvested portion provides

habitat for predators and parasites of pests

Alternatives to Pesticides• Biological controls – natural

predators, planting crops at proper times, etc.

• Problem: Some farmers import very effective predators invasive species

Alternatives to Pesticides• Artificial pheromones and hormones• Pheromone = chemicals produced by

animals to communicate with animals of the same species, usually to reproduce

• Hormone = chemicals produced to control body functions, like growth and metamorphosis

• Triggering early molting in larvae, abnormal development, etc. death

Alternatives to Pesticides• Sterile male technique – large

numbers of males are sterilized in a laboratory by radiation or chemicals and then released into the wild

• Especially effective in species where the female only mates once

Alternatives to Pesticides• Genetically modifying plants –

plants can be modified to be resistant to pests or so that insects that eat the plant can no longer reproduce

Alternatives to Pesticides• Quarantine = restriction of the

importation of exotic plant and animal material that might harbor pests OR block off an area where a pest is detected to prevent it from spreading to the entire crop

When to use pesticides…• Economic injury threshold =

the benefit of taking action (such as using pesticides) exceeds the cost of that action

Integrated Pest Management in Asia

• 1950s = rice farmers in Asia encouraged to use pesticides by scientists and chemical companies

• 1980s-90s = International Rice Research Institute (IRRI) encouraged integrated pest management

• Limited pesticide use, focus on eliminating pests with natural predators

Irradiating Food• Exposing food to ionizing radiation

(usually gamma rays) kills many bacteria and extends shelf life of many foods

• Controversial because irradiation forms traces of chemicals called free radicals that have been demonstrated to be carcinogenic in laboratory animals

Laws Controlling Pesticide Use

• Food, Drug, and Cosmetics Act (FDCA) = passed in 1938, recognized need to control pesticides in food, but did not provide a means of regulation

• Pesticide Chemicals Amendment = passed in 1954, aka the Miller Amendment, required the establishment of acceptable and unacceptable levels of pesticides in food

Laws Controlling Pesticide Use

• Delaney Clause = passed in 1958, stated that no substance capable of causing cancer in test animals or humans would be permitted in processed food

• Did not cover pesticides on raw foods• Did not cover pesticides that were used

prior to passing

Laws Controlling Pesticide Use

• Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) = passed in 1947 to regulate effectiveness of pesticides (protect people from buying pesticides that don’t work), but it has been amended to require testing and registration of the active ingredients of pesticides

Laws Controlling Pesticide Use

• Food Quality Protection Act = passed in 1996, controls use of pesticides on raw food as well as processed foods; reduces time it takes to ban a pesticide considered dangerous (10 years to 14 months)

Manufacture and Use of Banned Pesticides

• US companies manufacture pesticides that have been banned or restricted in the US and export them to developing countries

• Difficult to monitor or enforce international trade

• Unwanted pesticides are accumulating being stored in unsafe ways

Importation of Food Tainted with Banned

Pesticides• We ship out the banned pesticides

used to grow food we import the food• FDA can only inspect ~1% of food

shipments each year• Food importers sometimes sell tainted

food even after they are caught fines are not severe enough to discourage the practice

Global Ban of Persistent Organic Pollutants

• Stockholm Convention on Persistent Organic Pollutants = 2001, international treaty that seeks to protect people from the 12 most toxic chemicals on Earth

• Bioaccumulation, endocrine disrupters, cancer, etc.

• Countries required to develop plans to eliminate use of the “dirty dozen”

• Exception for DDT and malaria

Public Attitude• Pesticides help grow more visually

appealing food• Farmers using less pesticide for

their own health reduce exposure• Important to maintain balanced

perspective